tons of sudden issues, alternator?
 

05 x5, I don't drive it often. Primarily wife and daughter. Wife started reporting 4x4 and Brake light coming on, not all the time, intermittently. Daughter said that when it comes on you lose a lot of power.


I do keep it maintained and have the ECS/Schwaben scanner and haven't had much in the way of codes/errors. I scanned it after they reported having issues and there were a ton of codes and errors. Misfires, idle air controller, no communication DCS, no communication ABS, servotronic open circuit, torque limited, probably some others I'm forgetting.


I drove it with the scanner tool on the dash set to voltage. It held 13.4-13.6 volts and it drove fine. Then thought to turn on every electrical device I could think of. headlights, wipers, radio, still fine but then when I turned the AC on the whole dash lit up. Engine failsafe mode, 4x4, and brake. Voltage on the reader initially dropped to 13.1 and I even saw 12.9 for a moment. So think I'm pretty safe to just replace the alternator? Oh and as far the battery. It was showing 12.2 before I started it this morning.

Regulator going bad
Option 1 replace alt after smacking it with a rubber mallet to confirm not just the brushes stuck
Option 2 remove clean internals and replace the regulator and brushes
This info is based on your application being a 3.0 engine

I think that scanner is basically identical to foxwell in which case you can. GRAPH the voltage.

4x4 light will come on for a few other reasons but they will usually throw a code liked steering sensor or yaw sensor

If you have the valeo (sp) Alternaror I have DIY brush only refurbish that changes the polarity of the armature and will extend the life of the alternator a lot without having to pull the bearing to change the slip rings.

One slip ring takes 4-5x the abuse, swapping polarity and brushes will add 50-80% to the lifespan in 20-30 minutes (and another hour of remove and replace).

What engine? When you turned on AC and the voltage dropped did you check that the belt is moving normally and vibration damper (crank pulley) is not slipping on it's internal vulcanisation?

yeah 3.0 with valeo 140 amp. No I didn't check anything, I was driving it.



Here's the alternator, it does look like shit. PO had a power steering leak that I took care of.


https://i.imgur.com/jh4WNDL.jpg?1

I had an oil leak that exacerbated the problem worth worn out brushes and slip rings.

Search for the valeo slip ring and brush kit it was $20 when I bought mine. If you are fairly handy it's 5/10 difficulty at worst. If you do brush only with polarity swap 4/10.

I did the brush and rings swap on my car, did brush and polarity fix on wife's.

Alternator testing requires a AMP load and varied RPM test not just idle. What you are looking for is a simple stable amp/volt delivery. If your alt has 100K on it, soaked in oil, delivers 13.6+ voltage one second and battery voltage the next it is time for R&R (Remove and replace/repair)

If you choose the replacement path, buy a new unit that matches your current unit Brand/amp - see label on alternator back for details. Run from remain units as 50% will last.

Andrew has posted lots of info on rebuilding/replacing the regulator and brushes if you choose the rebuild path. Review his posts and ask for assistance if required.

Charts below show battery status and a tester that allows you to load the charging system to correct amp load and read Volts at idle, 1500, and 2500 RPM. Any competent shop can perform this test. A bench test of the alternator by your local parts store will get you what you pay for....

Just turn on high consumables (blower motor full speed, headlights, rear glass defogger, seat heating, etc...) checking the voltage should give a pretty good picture. Then turn on AC and turn the steering from side to side to put strain on power steering pump to see how vibration damper / belt behaves.

Unfortunately striaght load testing won't catch intermittent problems. Best way with typical tools is either use a DMM that has min/max capability or the likes of a foxwell scanner and graph the voltage during a test drive. The main symptom of worn brush/slipring end of life is a trrottke off coast to a red light the voltage will dip.

I would not even consider putting an alternator not even a brand new one before in take it to auto part store for a free load test.

It was fun taking my 17 yr old oil stained alternator to test after replacing the sliprings. The guy was sure that old as hell looking unit couldn't pass but did of course flying colors. Still going strong 3.5 years layer.

Did wife's last year hers failed fast and hard. Just stopped putting out enough voltage at the end of a 7 hr round trip from Chicago to Indianapolis.

I didn't want to wait the days for the slip ring kit, and found a hardware store locally that had the correct size brushes so I bought them and did a brush only swap.

Since one bush/slip ring pair takes 70% of the wear, I swapped the polarity so the opposite slip ring will now take the abuse. I was considering doing the polarity swap before the brushes wore out it should add 50% to the lifespan but I missed the opportunity.

If I ever have an option to get an alternator out and swap the polarity, when the alternator is about 5000 hours I will definitely do it.

Turning on the AC and the dash light up so it must be the Alternator. Reminds of the story of the deaf frog. A man taught a frog to jump when he said jump. The man remove one of the frog's front leg and yelled jump. The frog jump, but not very far. The man remove the frog's other front leg and yelled jump. The frog was still able to jump. The man removed the frog rear leg and yelled jump. With great effort the frog was able to hop on one leg. The man remove the last rear leg and yelled jump. The frog just sat there. The man continues to yell jump but the frog continues to sit there. The man's conclusion was that after removing all the frog's legs, the frog turns deaf.

Maybe the AC compressor is putting such a load on the engine that it is not able to spin fast enough to generate the needed voltage. Normally when the AC is turned on the idle speed is increased to compensate for the additional load. Could be the compressor is loading up the engine, but that just a guess on my part. This guess is base on the daughter's explanation/observation "that when it comes on you lose a lot of power".